There is a hair-hydration method that's easy to do at home, doesn't need expensive products and works on a greenhouse principle. It's called "bagging" and the idea is simple: apply a hydrating product, cover your hair with a plastic wrap or shower cap, and let body heat do the work.

The mechanism is real, not marketing: the heat creates a fine humidity that opens up the outer layers of the hair shaft and lets hydrating molecules sink deeper. Specialists call it "the mini greenhouse effect." The result: better absorption of the product, shinier, more elastic hair.

The method can be applied to the entire length of the hair or just to the ends - for the latter, small zip-lock bags slipped over the dampened ends do the trick. Important warning: bagging doesn't repair damaged ends permanently. Scissors do that, not products. Overuse can weaken the hair and trigger breakage.

Recommended products: lightweight hydrating conditioners, leave-in treatments and oils - argan or marula - without overloading. Common mistakes: piling on too much product, leaving it on too long, and expecting permanent results. Bagging is upkeep between salon visits, not a replacement for them. But for anyone with dry or color-treated hair, it's probably the most cost-effective thing you can do in 30 minutes at home.